Process of reducing zinc oxids.



o. F. BURGESS. PROCESS FOR REDUCING ZINC OXIDS. APPLICATION FILED 0OT.8,1909.

1,059,342. D Patented Apr. 22, 1913.

InvenIljr names F. Burgess .1 '1 A'Hurfis a T 0 all "whom, it mayconcern UNITED STATES PATENT OFFICE CHARLES IF. BURGESS, OF MADISON,WISCONSIN.

PROCESS FOR REIJUCING ZINC OXIDS.

Specification of Letters Patent.

, Patent-ed Apr. 22, 1913.

Application filed October 8, 1903. Serial No. 521,761.

Be it known that I, CHARLES F. Buaonss, a citizen of the United States,residing: at Madison, in the county of Dane and State of Wisconsin, haveinvented a certain new and useful Improvement in a Process for ReducingZine Oxids, of which the following is a .full, clear, concise, and exactdescription, reference being, had to the accompanying-drawings, forminga part of this specification.

My invention relates to a process for reducing zinc oxids.

According to the usual practice the zinc ore or oxid of zinc, isintimately mixed with carbon and the mixture is then subjected to heatin a clay retort, the vapors being condensed 1n a suitable claycondenser. In this a process it is possible to conduct the reducingoperations with only comparatively small quantities of ore in a singleretort. It is, therefore, necessary to use a large num- 'ber ofretortsin order to obtain any considerable production of metallic zinc.Moreover in this method of reduction there is considerable loss of heatowing to the necessity of heating through the walls of the clay retorts.It is customary in mixing the charge to use a considerable excess ofcarbon for the reducing action and even then the reduction of the ore isby no means complete. In order to avoid corrosion of the walls of theretort, it is necessary to employ a high grade ore with a low content ofiron and other inpuritics.

Numerous methods have been tried for smelting zinc ores electrically,but in all of these, so far as I am aware, an intimate mixtureofthezi'nc ore and the carbon,

which acts as a I'GdlilClnQ agent, is employed.

The method which forms the subject of this invention consists inmaintaining the Zinc ore and the carbon entirely separate from eachother. In the preferred form of my process, the zinc ore is heatedelectrically and zinc oxid is thereby volatilized. Simultaneously a massof carbon is subjected to a current of electricity to heat it to aproper reducinp temperature and the vapors of zinc oxid from the ore arethen brought into contact withith'e mass of carbon. In this way it isapparent thatthere is an intimate association of the vapor of the zincoxid with the glowing carbon and not be raised to such a point thatother oxids or impurities will be volatilized with the zinc. Myexperiments have shown that zinc oxid may be completely removed fromordinary roasted zinc ore by the method which I have just described.

The mass of carbon is maintained at a temperature which is adapted tocarry on the reducing action on the vapors oi. the

oxids of zinc which are brought into contact with the carbon. Theadvantage of this feature of my invention is very considerable, inasmuchas the proper temperatures for volatilizing zinc oxid and for conductingthe reducing operation are not the same, the proper temperature of thecarbonbcing considerably lower than that which is 1'0- quired tovolatilize the zinc oxid.

After the zinc oxid has been completely volatillzcd from the ore, theresidue may be removed from the volatilizing chamber preferably in theform of a molten slag.

The liquefaction of this residue may be in-v sured, where necessary, bythe addition of suitable fluxinp; agents, as, for cxamplc,lime.

liy intermittently charging the zinc ore into the volatilizing chamberand removing the residue in the form of molten sing, it is evident thatthe volatilizing action may be made continuous. Similarly, as the carbonis burned by the oxygen given out from the volatilized oxid of zinc, theashes formed thereby maybe removed from time to time and additionalcarbon added in the reducinp chamber. The operation of the furnace,

as a whole, is thereby rendered continuous with the consequentadvantages of increased output and reduced cost of operation besides theother advantages whlch I have described above. These and otheradvantages i chamber A are electrodes4-4 suitably conmeans ofheating andvolatilizing the volanace is a second chamber B, connected with 4 besatisfactorily-used,'inasmuch as there is ber B is provided with aconducting plate 9 A hopper-13, having a cover 14 is placed at the topof the furnace and it is through this.

suitable refractory material. The exact naployed depends largey on thenature of-the "add lime to the ore,-all portions of the cham-.

may be formed from the ore.

with the walls of the chamber,- as is the case will be more apparent byreference to the drawings, in which-- Figure 1 is a diagrammaticvertical section of one form of a smelting'furnace. Fig. 2 is. atransverse section on the line 2---2 of Fig. 1, Fig. 3 is a diagrammaticsectionof a modified form of furnace, and Fig. 4 is a diagrammaticvertical section of a second modified form of furnace. Referringto Figs.1 and 2, the furnace is rovided with a' vaporizing chamber A havmg walls1-1, a bottom or hearth 2, and a roof 3, which are built of fire brickor other ture. of the refrac'tor brick which are eIIT- j ore which is tobe smelted. If, in order to obtain .a'more liquid slag, it is desired toher which come -11). contact with the. ore should be built of magnesiteor other-basic brick. If, on the other hand, it is desired to make noadditions of. lime or other basic material, the sla maybe of an acidchamp- 'ter, as iswell un erstood by those skilled 1n the art, andsilica brick should be employed.

Projecting: through thewalls 1-1 of the nected to a source of electricpower. These electrodes are adapted to form an are between their ends,this am serving as the tile oxid from the ore.

v A hopper 5 is provided in theroofwof the chamber A, this hopper havinga cover 6; In the lower part of the chamber A is a tap. hole 7 which isordinarily filled with sand or magnesite according to the nature of thebrick of which the interior of the chamber is constructed. This tap-holeis for the urpose of periodically drawing off slag w ichlIAssociatedwith the chamber A of the furtlie chamber A by the flue 8through which gases may pass from chamber A to chamber B. Chamber B isbuilt oflsome form' of refractory fire brick. Ordinarily silica .brickmay no basic slag which may come in contact with chamber A. The bottomof the chamof graphite or other similar material which. acts as anelectrode, this plate 9 being connedt'ed with a source of electricitythrough the conductorftQ. Toward the upper art of chamber Bis ravided aring 11 of similar material'whic acts as a second electrode and isconnected Withthe second pole of the source ofpower through theconductor 12.

hopper that the carbon 15, with which the 'as .resistance in theelectric circuit.

chamber B is filled, may be added. Two

outgoing fiues 16 and 17 are provided toward the upper part of thechamber B. To ward the bottom of chamber B is provided a door 18 throughwhich the ashes of the burned carbon 15 may be readily removed,

The operation of my furnace will now be readily understood. 1 p

Ore is first added to the chamber: A.- through the hopper 5. Heat beinggenerated by means of the arc formedbetween the electrodes 4;4, the oreis gradually heated and the zinc oxid is volatilized, the residue of theore forming a molten slag 19, a fresh addition of ore being representedat 20. Si-

the proper temperature, this carbon acting It is clear that there is butlittle access of air to chamber B and for this reason, the carbon willnot be burned when heated merely by the electric current flowin betweenthe electrodes 9 and 11. After t e vapors of zinc oxid pass from thechamber A through the flue 8 to the chamber B, it is clear that therewill be an'intimate contact between these vapors and the reducingcarbon.The oxygen from the vapor will now be given up to, the carbon and thereaction;

will take place. Thevapor continues to rise in the chamber B, thereducing action continuing' until all vof the zinc oxid has beenreducedto the vapor of metallic zinc. The

reduced vapors then pass outwardly through the fiues Mind 17 and arethen condensed by any of the well known methods. The consumption of--carbon, which is preferably in' the form of coke, is very limited,inasmuch as the only oxidizing action on-this carbon is that of theoxygen from the vapors of zinc oxid. I

A modification of my furnace is shown in Fig: 3, in which the chamber Ais placed directly below the chamber 'B. The ore is added. through thehopper 5 which is provided with an. extension 21 which passes through.the side of the furnace intothe chamber A. The disposition of the electrodes 4-4, and the tap-hole 7 is similar to vject of the bell 23 is toprevent the carbon 15 from dropping into the chamber "A.

With the difierences which have just been pointed out,.the-operation ofthe modifica;

tion shown in Fig. 3 is otherwise identical with the form illustrated inFigs. 1 and 2.

In Fig. 4 a second modification is shown.

The outside of the chamber B corresponds with the outside of thefurnace, and the chamber A occupies a position inside of the chamber Band in the lower part of the same. The electrode 9 is placed at thebottom of chamber B and just below chamber A. As the current flowsbetween the electrodes 9 and 11, the mass of carbon 15 is thereby heatedand on account of the smaller cross-sectional area of that portion ofthe carbon which lies in the same horizontal plane with the chamber A,this portion will thereby become heated to a higher temperature thanthat attained by the carbon above the chamber A. The heat from theportion of carbon lying opposite the chamber A .is conducted through thewalls of this chamber and the ore is thereby heated byreduction and thezinc oxid is readily volatilized. Chamber A is rovided with a roof 25retained in position by supports 26 between which there are spaces 27.The object of the roof 25 is to prevent the carbon 15 from falling intothechamber A. The tap-hole 28 enters the lower part of chamber A and itis through this tap-hole that the molten slag can be removed. Withtheexception of the modifications which We have described, the operation ofthe furnace illustrated in Fig. 4 is the same as that of the furnacesshown in Figs. 1, 2 and 3.

Although I have described my process of reducing ores as applied particuarly to ores of iinc, I do not wish to confine myself to the ores ofthis,metal, inasmuch as my process also has application in the smeltingpf otheruores, as, for example,antimony, blS- ninth, lead, etc.

Many modifications can be made from the exact process .which I havedescribed without departing from the spirit of my invention. Forinstance, it is obvious that the necessary heating might be doneotherwise than electricallyalthough, as I have said, in the preferredmanner of carrying out my rocesselectricity is used as the source oflieat.

What I claimas new and desire to cover by United States Letters Patentis:

1. The process of reducing aihc oxid which consists inelectrically'heating said oxid to. a temperature sufficient to producevolatilization, simultaneousl heating a mass of carbon, andCOIldIlClilIl the vapors of the zinc oxid into contact with the mass ofcarbon.

2. The .process of reducin zinc oxid which consists, in electricallyieating said oxid to a temperature sufficient to produce volatilizationin one chamber, simultaneously heatin a mass of carbon in a secondchamber, and conducting the vapors of the zinc oxid from said firstchamber to said.

temperature sutlicieiit to produce .volatilizaP tion, simultaneouslyheatm a mass of carbon to a temperature suitab e to produce reduction,and conducting the vapors of the volatilizcd zinc oxid into contactwiththe heated carbon;

The process of reducing oxids of zinc which consists in electricallyheating a mass of carbon to a suitable redueingtemperature in onechamber, simultaneouslyheating-the oxid of zin c to a suitablevolatilizing terriperature in a second chamber, and conducting thevapors of said volatilized zinc oxid from said second chamber into saidfirst chamber.

6. The process of reducing zinb ore which consists in heating the oretoa temperature sutlicient to volatilize zinc oxid, simultaneously heatinga mass or carbon to a reducing,

temperature, and conducting the, vapors of said zinc oxid into contactwithsaid carbon.

7. The process of reducing metallicoxids which consists in heating saidoxids by an electric arc to a temperature sufficient to producevolatilization, simultaneously heating a mass of carbon included asresistance in an electric circuit,-and bringing the vapors ofthe'metallic nxids in'to contactwith the mass of carbon.

8. The process of reducing metallic ores whicl1.consists in heating a,mass of carbon by including said carbon as resistance in an electriccircuit, simultaneously heatingthe metallic ore to a temperaturesufficient to volatilize the oxid of the metal of said ore, andconducting the vapors of the volatil'izcd bxid into contact with themass of carbon.

9. The process of reducing oxid of zinc which ronsists in heating a massof carbon by including said carbon as resistance in an electric circuit,simultaneously heating the zinc oxid to a temperature to producevolatilization, and conducting the vapors of the volatilized oxid intocontact with the a mass of carbon.

10. The process of reducing zinc oxid which consists in heating saidoxid to. a temperature sufficient to volatilize the same, conductipg'the vapors of the zinc oxid into contact with suitable reducingmaterial, and condensing the vapors of zinc.

'11. The process of reducing metallic oxids which consists inheating,said oxids to a ore separate from-the carbon.

. conducting temperature sufiicient to volatilize the same, the vaporsof the metallic oxid into contact with suitable reducing material, andcondensing the vapors of the reduced metal. 7

12. The process of reducing zinc ore which consists in heating the oreuntil zinc oxid is evolved, and conducting the zinc oxid into ontactwith heated carbon, while maintainng the ore, separate from the carbon.

13. The process of reducing metallic ores which consists-in heating theore until the oxid of the metal of said ore is evolved, and conductingthe metallic oxid into contact with heated carbon, while maintaining the14. The process of reducing metallic ores which consists in heating theore until the metal compound of said ore is volatilized, and conductingthe vapors of said compound into contact with a suitable reducingmatefrom the reducing material.

rial, while maintaining the ore separate 15. In the process of reducingzinc-ore, the step which consists in conducting? the vapors of zinc oxidformed into contact with heated carbon, while maintaining the oreseparate from the carbon.

16. In the process of reducing metallic ore, the step which consists inconducting the vapors-of the metallic oxid formed into contact withheated carbon, while maintaining the ore separate from the carbon.

17. The process of reducing zinc oxid which consists in heating saidoxid to a temidrawing off the reduced f vapors from the top of saidsecond chamber and from a zone perature sufiicient to producevolatiliaation, simultaneously heating a mass of carbon to. atemperature suitable to produce reduction, and conducting the vapors ofthe volatilized zinc oxid upwardly through the interstices between theparticles of said mass? 18. The process of reducing zinc oxid whichconsists in heating said oxid to atemperature sufficient to producevolatilization, simultaneously heating a column of carbon to atemperature suitable to produce reduc* tion, introducing the zinc oxidvapors into the interstices between the particles of said column atIthebottom thereof, and'drawing oil the reduced vapors from the top of.said top and bottom thereof.

19. The process of reducin zinc oxid which consists in electricallyheating said oxid to a temperature sufficient to produce volatilization'in one chamber,' simultaneously heating a mass of carbon in a secondchamber, conducting the zinc oxid vapors to the bottom of said secondchamber, and

intermediate of the top and bottom thereof.

In witness whereof, I hereunto subscribe my name. this 2nd day ofOctober, A." D. 1909.

CHARLES E. BURGESS} Witnesses I v HENRY CAssoN, Jr, ANNA B. LUCK.

